The present invention relates to a magnetic disc apparatus, and more particularly to a magnetic head positioning assembly for use in a magnetic disc apparatus.
FIG. 1 illustrates, partly in section, one example of a conventional magnetic disc apparatus and FIG. 2 illustrates, in perspective, a magnetic head positioning assembly for use int he magnetic disc apparatus. Such a magnetic disc apparatus is disclosed in Japanese Patent Application Laid Open No. 58-220275.
Referring to the figures, the magnetic disc apparatus comprises a base 10, a magnetic disc driving assembly 20 mounted on the bae 10 for supporting and driving magnetic discs 12 thereon and a magnetic head positioning assembly 30 disposed on the base 10 in a predetermined positional relationship with respect to the magnetic disc driving assembly 20. The magnetic disc driving assembly 20 comprises a rotary shaft 14 for supporting magnetic discs 12 and a motor 16 for rotatably driving the rotary shaft 14. The magnetic head positioning assembly 30 comprises an arm assembly 32, a rotary shaft 34 to which the arm assembly 32 is secured, a housing 36 secured at the bottom portion 37 (see FIG. 2) thereof tot he base 10 by means of a plurality of set screws 50. The rotary shaft 34 is pivotaly mounted in the housing 36 through bearings 38a and 38b. The arm assembly 32 comprises arm members 40, each being provided at one end portion thereof with a magnetic head 42. The head positioning assembly further comprises a magnet assembly 44 disposed at an opposite side of the shaft 34 with respect to the arm assembly 32. Themagnet assembly 44 includes a magnet housing 46 having an E shaped magnet 48 housed therein and a coil assembly 52 of a linear D.C. motor, which is movably mounted on the center leg of the E shaped magnet 48. The magnet assembly 44 is mounted on the bottom portion 37 of the housing 36 of the head positioning assembly 30 by means of screws 54 from the bottom side thereof.
In the thus-constructed conventional apparatus, when a current i flows through the coil assembly 52, the coil assembly 52 is swung about the rotary shaft 34 due to an electromagnetic forge generated therein, and the arm assembly 32 is moved about the rotary shaft 34 as indicated by an arrow R or S in FIG. 2, as the coil assembly 52 is swung, so that the magnetic heads 42 are shifted to an objective track on the magnetic disc 12. Accordingly, when a current i is applied to the coil assembly 52 in one direction, the coil assembly 52 is swung in a first direction with respect to the case as indicated by the arrow S in FIG. 2, whereas when the current i is passed through the coil assembly 52 in the other direction, the magnetic heads 42 are shifted in the other direction as indicated by the arrow R in FIG. 2, i.e. toward the periphery of the magneti discs 12. Thus, the magnetic heads 42 can be moved to a desired position on the magnetic discs 12 to read and/or write data on the magnetic disc 12.
Such a conventional magnetic disc apparatus has problems in that it is difficult to accurately mount the head positioning assembly 30 on the base 10 in a predetermined positional relationship with respect to the disc driving assembly 20 during assembly of the magnetic disc apparatus. Therefore, the magnetic head positioning assembly 30 is first adjustably moved such that the pivot axis of the rotary shaft 34 is positioned in a predetermined positional relationship with respect tot he shaft center of the disc driving assembly 20 on the base 10. Then, a bore is made both in the bottom portion 37 of the housing 36 and the upper surface of the base 10. Finally, a bolt 50 is screwed into the bore to fixedly mount the assembly 30 on the base 10. Thus, assembly is both time consuming and troublesome.